1. Field of the Invention
The present invention relates to a data transfer checking system for checking if data is written correctly in the initial loading of a microprogram or the like in an electronic computer system.
2. Description of the Prior Art
FIG. 4 shows the essential part of a data transfer checking system for an electronic computer system. The checking system includes an electronic computer 1 having a processing unit 2 controlled by microprograms and a control memory 3 for storing microprograms; an external memory or storage 4 (hereinafter "external memory") for storing microprograms in files; a service processor 5 for controlling the processing unit 2 and performing the initial microprogram loading into the control memory 3 from the external memory 4; an input/output (I/O) unit 6 for inputting/outputting data or commands; a system bus 7 for transferring data between the service processor 5 and the control memory 3; and a processor bus 8 for interconnecting the service processor 5 and the processing unit 2.
FIG. 5 shows how the conventional data transfer checking system works. Microprograms to be stored in the control memory 3 for controlling the processing unit 2 have been stored in the external memory 4 in files. When initialization of the system is started by turning on the system or inputting a command into the service processor 5 through the I/O unit 6, the microprograms are stored in the control memory 3 by the initial microprogram loading process. The initial microprogram loading process can also be performed by inputting a command as described above.
A microprogram is read out of the external memory 4 into the service processor 5 (Step S1) and loaded into the control memory 3 via the system bus 7 (Step S2). These steps are repeated until all of the memory areas in the control memory 3 are loaded with microprograms.
Upon completion of the loading, the service processor 5 performs a readback checking procedure for checking if the microprograms are loaded correctly. That is, the service processor 5 reads out the contents of a microprogram in the control memory 3 via the system bus 7 (Step S3) and those of the external memory 4 corresponding to the contents (Step S4) to compare both of the contents (Step S5). These steps are repeated for all of the microprograms in the control memory 3. If all of the contents are matched (Step S6), the loading is a success (Step S7). If there is a mismatch, a loading error correcting procedure is performed (Step S8).
In the conventional data transfer checking system, the service processor 5 must read out the contents from the external memory 4 to compare them with the contents in the control memory 3, resulting in the increased number of data read cycles by the service processor 5. As a result, it is increasingly difficult to speed up the checking process of the contents of loaded microprograms.